I'm very very bad with CSS (I do not understand syntax at all), I'm just using my knowledge to tinker with code. I'm using Chrome with Stylish addon, and I want to make dark wikipedia but with my preferences. I took some code from stylish and just changed colors, but now it's something new where I have to add stuff so I'm stuck. It's obviously made in chrome, so it's temporary. This is my problem:
And my question is how to make that box opaque with like #555 color, without destroying everything else.
Here is code that I'm using: pastebin.com